Method of controlling a turbocharger

Abstract

A variable-volume turbocharger device comprises at least two exhaust gas passages (A), (B) different in the flow characteristics, divided by a partition wall (20) provided in a turbine housing (18), and two valve members (34a), (34b) which are actuated so as to open and shut the exhaust gas passages (A), (B). The valve members (34a), (34b) each are actuated to open and shut in response to the speed and load of an engine or the likes, whereby either one of the exhaust gas passages (A), (B) or both of them are opened to provide at least three turbine flow characteristics. An exhaust gas turbine (12) can be thereby operated with remarkably good efficiency suitable to the operating state of the engine.

What is claimed: 
     
       1. A method for controlling a variable-volume turbocharger device for use with an engine comprising: an exhaust gas turbine including a turbine rotor having an axis, said exhaust gas turbine being formed with a discharge end and with two scrolls divided in the direction of the axis of the turbine rotor by a partition wall provided in a turbine housing at its discharge end thereof, one of said scrolls forming a first exhaust gas passage having a large exhaust gas flow area, the other scroll forming a second exhaust gas passage having a small exhaust gas flow area;   an exhaust manifold connected to said engine and the exhaust gas inlet side of said turbine housing;   a first valve means pivotally and rockingly mounted at the exhaust manifold side so as to open and close said first exhaust gas passage;   a second valve means pivotally and rockingly mounted at the exhaust manifold side so as to open and close said second exhaust gas passage;   a first actuator operative to open and close said first valve means;   a second actuator operative to open and close said second valve means, and   a valve control means for operating said first and second actuators in response to the speed and load state of said engine, said method being such that said first valve means is actuated to be closed and said second valve means is actuated to be opened by said valve control means when said engine speed is low and said load is high, and that said first valve menas is actuated to be opened and said second valve means is actuated to be closed when said engine speed is medium and said load is high, and that both said first and second valve means are actuated to be opened when said load is low irrespective of the engine speed or when the load is high and the engine speed is high, whereby three different turbine flow characteristics can be obtained.   
     
     
       2. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which said first and second valve means are actuated to be opened simultaneously. 
     
     
       3. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which said second exhaust gas passage is disposed in a position nearer to a compressor of the turbocharger device than said first exhaust gas passage. 
     
     
       4. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which said first and second valve means are formed in a flat-plate shape. 
     
     
       5. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which both the valve means are actuated so as to be completely closed at the saem time, whereby an exhaust braking function can be exhibited. 
     
     
       6. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which said valve means are further controlled in actuation in response to the state of depression of an accelerator pedal, and when said accelerator pedal is released, only one of said valve means is actuated to open so that said small flow characteristic can be obtained. 
     
     
       7. A method for controlling a variable-volume turbocharger device, as set forthin claim 1, in which said load state of the engine is detected by the accelerator opening of the accelerator pedal, and in the low load state of the engine in which the accelerator opening is lower than a set value, only one of said valve means is actuated to open so that said small flow characteristic can be obtained. 
     
     
       8. A method for controlling a variable-volume turbocharger device, as set forth in claim 1, in which said valve means are further controlled in actuation in response to the speed changing state of a transmission, and when said transmission is in a neutral position, only one of said valve means is actuated to open so that said small flow characteristic can be obtained.